Torsion springs are frequently used on micromechanical elements if they are to be pivoted about an axis in an oscillating fashion. For example, such torsion springs can be connected to plate-shaped elements with which electromagnetic radiation can be reflected. Depending on the pivot angle the angles of the reflected radiation then change.
The entire structure is manufactured here using a microstructure technology which is known per se and also by means of etching methods for etching out of a substrate, frequently silicon.
Owing to the manufacturing technology, the torsion springs usually have a rectangular, square or trapezoidal cross-sectional geometry. However, with these cross-sectional geometries, bulges occur in the cross-sectional faces in the direction of the torsion axis when the elements are deflected. This leads in turn to extensions at clamping end points of the torsion spring and increased tensile stresses which can lead to a fracture. As a result of such extension, the restoring forces are increased, which in turn leads to an increase in a spring stiffness/spring constant. However, since the restoring force of an element to which tensile stress is applied rises progressively with the extension, the fixed clamping gives rise to a progressive, that is to say nonlinear spring characteristic curve.
In order to counteract these disadvantageous effects, slots which are oriented orthogonally with respect to the longitudinal axis of the torsion springs and the torsion axis and which are arranged behind the clamping end point are formed on clamping end points of torsion springs.
In other cases, bent torsion springs were used.
A spring characteristic which is as linear as possible over the respective deflection range when pivoting occurs is aimed at.